1. Field of the Invention
The present invention relates to a cartridge case having a tape reel including a cylindrical bottomed hub, a lock member for stopping the rotation of the tape reel, and to an information recording medium having the cartridge case.
2. Description of the Related Art
Heretofore, there is known a single reel type tape cartridge having a single tape reel accommodated in a case main body as an information recording medium capable of recording a large amount of data. In this type of the tape cartridge, when the tape cartridge is mounted on a drive unit, a magnetic tape can be wound by rotating the tape reel by engaging a drive teeth portion formed to an outside surface of a bottom plate of a hub of the tape reel with a drive teeth portion formed to a drive shaft of the drive unit. Further, when this type of the tape cartridge is not used, the rotation of the tape reel can be stopped by engaging a locking teeth portion formed on an inside surface of the bottom plate of the hub of the tape reel with a locking teeth portion formed to a lock member in the case main body. In this case, to rotate the tape reel smoothly, a predetermined clearance must be provided between the tape reel and the case main body. Accordingly, in this type of the tape cartridge, since the tape reel shifts in the case main body by the amount of the clearance, the tape reel may be decentered (misaligned) from the drive shaft of the drive unit, and thus the drive teeth portions thereof may not be perfectly engaged with each other, from which a problem arises in that it is difficult to wind the magnetic tape in such a case. Further, since the tape reel shifts in the case main body, the tape reel is decentered from the lock member, and thus the locking teeth portions thereof may not be completely engaged with each other, from which a problem also arises in that the tape reel may be imperfectly locked and the magnetic tape wound around the tape reel may be loosened in such a case.
As a technology capable of solving the above problems, Japanese Laid-Open Patent Publication No. 2002-343058 discloses a magnetic tape cartridge having a rib formed on an inner peripheral surface of a reel hub (hub) of a reel (tape reel). In the magnetic tape cartridge, the clearance between the end of the rib and an outer peripheral surface of a lock member is reduced in a locked state in which the locking teeth of the lock member is engaged with the locking teeth of the reel. As a result, even if the magnetic tape cartridge is set to the drive unit in, for example, a longitudinally mounting state (the axial line of the reel is in an approximately horizontal state), since the rib is abutted against the outer periphery of the lock member, the shift of the lock member and the reel locked by the lock member is regulated. Accordingly, the reel is prevented from being decentered from a rotational drive member (drive shaft) of the drive unit, and the reel is prevented from being decentered from the lock member, thereby respective tooth (gears) can be securely engaged with each other.